This application claims priority to the German Application No. 10139953.7 filed Aug. 21, 2001 in Federal Republic Germany.
1. Field of the Invention
The invention relates to a material for a metal strip for manufacturing electrical contact components.
2. Description of Related Art
Plug contact connections are widely used in electrotechnical applications. By this is understood, basically, a mechanical device made of a plug and a plug sleeve for opening and closing an electrically conducting connection. Plug contact connections are used in the most varied application fields, as, for example, in the automotive electrical field, messaging technology or the electronics of industrial plants.
A usual manufacturing method of such plug contact elements is to stamp out blanks from a copper or copper alloy strip, and to process these further into plug contact elements. Copper has a high electrical conductivity. To protect against corrosion and wear, as well as for increasing surface hardness, the copper or copper alloy strips are first tinned. Because of its good resistance to corrosion, tin is particularly suitable as a coating material for copper. The application of the coating by hot dipping is a standard technical procedure.
In this context, the most widely different tin alloys are known for surface coating the base material, in particular also tin-silver alloys, since these count among the very good contact materials.
It is known from European patent document 0 443 291 B1 that one may coat the base material of one plug element of a plug connector pair with pure tin or a tin-lead alloy, while the other plug element has a harder surface coating, applied in a molten fashion, made of an alloy containing up to 10% by weight of silver. Aside from silver, a number of other alloying metals is proposed. This approach points in the direction of producing qualitatively high-grade plug connectors having durably low contact resistance and requiring plugging and unplugging forces that are as low as possible.
DE 36 28 783 C2 describes an electrical connecting piece made of a copper alloy having 0.3 to 2% by weight of magnesium as well as 0,001 to 0.1% by weight of phosphorus. The electrical connecting pieces are distinguished by their strength, their electrical conductivity and voltage relaxation properties at raised temperatures. They demonstrate satisfactory application properties, even when made in compact sizes and complicated shapes.
On account of DE 43 38 769 A1, a copper alloy for producing electrical plug contacts also counts among the related art, which has a composition of essentially 0.5 to 3% by weight of nickel, 0.1 to 0.9% [by weight] of tin, 0.08 to 0.8% by weight of silicon, 0.1 to 3% by weight of zinc, 0.007 to 0.25% by weight of iron, 0.001 to 0.2% by weight of phosphorus, as well as 0.001 to 0.2% magnesium, the main component of the rest being copper and including unavoidable impurities.
The known metal strips, or rather the plug contacts made from them have proven themselves in practice. However, technical and qualitative requirements on the contact components, with respect to mechanical and electrical properties are rising increasingly. This applies particularly to the use of contact components under difficult or aggressive environmental conditions, such as for plug contacts in automotive electrical systems, and here above all in motor electronics. Under such difficult application conditions, requirements, above all with respect to temperature stability, relaxation stability, resistance to corrosion and adhesive strength of the coating may appear, with respect to which the known contact components come right up to their limitations. This may lead to peeling of the surface coating.
It is an object of the invention to create in an economically advantageous manner a material for a metal strip, for manufacturing electrical contact component parts, which combines good electrical and mechanical properties with improved adhesion between the base material and the coating.
These and other objects of the invention are attained by a material for a metal strip for manufacturing electrical contact component parts, which, expressed in percent by weight, has the following composition:
The remainder is copper and includes impurities caused by smelting.